ORDER II 



FORAMINIFERA 



31 



Subtaiiiily (J. Polymorphininae Brady. 



Test composed of Chambers arranged spirally or irregularhj ahout the long axis ; 

 aperture usually radiale. 



Polymorphina d'Orb. (Fig. 17, B). Segments irregularly helicoid, or 

 arranged biserially, more or less enveloping one another and variable in shape. 

 Terminal aperture round. Trias to Recent. 



Dimorphina d'Orb. (Fig. 17, C). Early Chambers irregularly or triserially 

 arranged, later ones foUowing in rectilinear fashion. Cretaceous to Recent. 



Subfaniily D. Uvigerininae Cnshman. 



Test composed of Chambers arranged triserially ahout the long axis ; aperture 

 usually simple, with a deficite neck and a phialine lip. 



Uvigerina d'Orb. (Fig. 17, E). Segments dissimilar, disposed in triple 

 series, and spirally wound like a gastropod shell. Eocene to Recent. 



Subfamily E. Ramulininae Brady. 



Test composed of Chambers with long tuhulariform tubes. 



Ramulina Rupert Jones. Test branching, consisting of rounded Chambers 

 joined by stolon-like tubes. Recent, and possibly also represented in the 

 Cretaceous. 



Family 7. Globigerinidae Carpenter. 



Test free, calcareous, perforated by coarse tubules ; monothalamous or poly- 

 thalamous ; Chambers globular, either irregularly disposed or imperfectly spiral. 



Of the tvvo principal genera belonging to this family, Orbulina d'Orb. (Fig. 

 18, A) is unilocular, and GloUgerina d'Orb. (Fig. 18, C) is multilocular. The 

 individual Chambers 

 usually open into a 

 common central 

 canal. In both 

 genera the test is 

 often covered with 

 extremely delicate 

 calcareous spines, 

 which, however, are 

 very easily broken 

 off, and are never 

 preserved intact in 

 the fossil State. 

 Both these genera 



are excessively abundant in existing oceans (Globigerina ooze) ; they occur 

 sparingly in the Trias and throughout the Mesozoic, first becoming important 

 during the late Tertiary. 



Sphaeroidina d'Orb. (Fig. 18, B). Characters few, so coiled as to form a 

 nearly globular test ; aperture with a valvulär lip. Cretaceous to Recent. 



Fig. 18. 



A, Orhulina universa Lam. Pliocene ; Sieniia, Italy, B, Sphaeroidina 

 austriaca d'Orb. Miocene Tegel ; Baden, near Vienna, C, Globigerina con- 

 glomerata Schwager. Pliocene ; Kar Nikobar Island, a, Inferior siirface ; 

 h, Superior surface ; c, Portion of periphery ; d, Transverse section enlarged. 



